We read with great interest the work by Alraies et al published in a recent issue of The American Journal of Cardiology . The authors’ work is commendable where they have reexplored the relation between the ratio of early transmitral flow velocity (E) to mitral annular velocity (E′) and pulmonary capillary wedge pressure in constrictive pericarditis (CP). Their study results demonstrated no significant correlation between the E/E′ ratio and pulmonary capillary wedge pressure and were in contrast to a previous small-sized study that reported an inverse correlation between these 2 parameters (annulus paradoxus). These study results were derived from a relatively larger patient cohort and questioned the validity of annulus paradoxus phenomenon. However, we would like to refer to another recent study from the Mayo Clinic that reported significantly lower E/E′ ratios at the medial mitral annulus in patients with CP (5.8; confidence interval 3.6 to 9.3) compared with the patients without CP (16.1; confidence interval 11.6 to 21.2, p <0.001). The Mayo Clinic study was conducted on 130 surgically confirmed patients with CP and is perhaps the largest study on this subject so far. The findings from the Mayo study again potentially strongly favor the presence of annulus paradoxus, although a direct correlation of E/E′ ratio with left-sided filling pressures was not performed, which would have in fact been confirmative. Nonetheless, the variable findings from these different studies now call for the need to restudy this relation in a future large-sized controlled prospective investigation.

The results from the future investigations would be able to help formulate a good pathophysiologic explanation of the correlation between these echocardiographic parameters. If indeed there is no significant correlation found between the E/E′ velocity ratio and left-sided filling pressures in prospective studies, it would confirm that the diagnostic utility of annulus paradoxus in CP is limited and this would call for a revision of the recently published pericardial disease guidelines, which emphasize the utility of E/E′ ratio as an estimate of left ventricular filling pressures in patients with CP.